Lapping device for cylindrical objects



April 25 1933 H. w. DUNBAR Er AL 1,905,821

` 1 LAPPING DEVICE FOR CYLINDRICAL OBJECTS Filed March 15, 1929 Patented Aer. 25,1933

UNITED STATESy PATENT. ori-'ICE Howaiin w. DUNBA'B AND .Tomil c. ram, or woiicEs'rEB., mssacmisms, as-

SIGNQRS T0 NORTON COMPANY, 0F SETTS, QOBPORATIQH Ol' IASSLCHU f -Lnifrimi nEvicE ron.

CYLD'DBIGAL OBJECTS Application tiled Hai-cli 15, 1929; Serial No. 347,298.

4finishing the surfaces of cylindrical objects such as the pin of a crankshaft.

In orderto finish the surfaces of various types of cylindrical objects, such as the bearings and pins of a crankshaft, it has been clistomary to rotate theobjects to be lapped between substantially stationary abrasive lapping blocks which are suitably mounted to permit the rotation of the work piece. This operation necessarily causes considerable wear on the laps themselves and necessitates 'renewal of the laps periodically. It has therefore been suggested that a iiexible abrasive paper be utilized in' placeof the solid laps heretofore employed'and that this paper be looped around the work piece and h'eld in position thereagainst by clamping jaws. -The abrasive paper is shortflived o l to the inherent nature of the material so t at it is necessary to replace the paper in the lapping zone frequently with a fresh portion; hence in theuse of such material the operator has to watch the lapping operation and observe the condition of theylexible abrasive paper and periodicallymove the paper along to a new position to bring fresh abrasivegrai'ns into contact with the workpiece. This has Ainvolved considerable attention on the part of the operator to make sure that heis performing each lapping operation'the sameas the one before and consequently has introduced a source of error or of diiculty in :operating thedevice. E

It is one objectof this invention to provide a lapping device, lin which a exible abrasive strip is utilized to ,lap the work, which .includes afmechanism capable of o erating automatically to. move -the ilexib e abrasive stripand renew the abrasive mate- 1 objectsl as a cran rial-in the lapping zone;

A further o ject of the invention is to provide a lapping device capable o'flappiiigsuch in andV which i's so constructed and arranged that a strip of 'flexible abrasive'iiiaterial is utilized for the lapping operation-and this material is movedv to pre'- 'sent a -fresh lapping surfacewhen a given piece of -work has been finished andV another piece of work is tobe inserted in the machine thus insuring that all of the pieces are lapped by the same type of material and consequently to the same extent;

.vide a la ping device primarily useful for lapping t e pins of a crankshaft which is so constructed and arranged that a flexible stri of lapping material may beemplyed for this pur se and this material will be fed autovmaticallyto present a 'freshsurface to the work whenthe clamping jaws which sup ort the work against 4the paper are opene to pei-mit the insertion ofa new piece of work therein..

A further object is to provide a freely movable jointed device for supporting the lapping paper and clamping arms during the lapping operation and which is so arranged that the arms may be locked in a stationary .position invention resides the combination of parts 175 set forth'in the s cification and covered the claims appen ed heizeto. E

Referring to the drawing which illustraties one embodiment of this invention, and in which like reference numerals indicate like arts: ,l p Fig. 1 is aside elevation of one ofthe lapping devices; l

' Fig. 2"is a similar view showing the parts in their respective positionsifor theilappmg operation; v

Fig. 3 is a sectional plan view taken on the `line 3 3 in Fig. l; l

Fig. 4-is an enlarged'lsectional side .elevation Aof a detail of the feeding mechamsm in one of the lapping devices;V o O Fig. 5 is an enlarged detail sectional view, taken along the line-55in Fig. 1; and

Fig. 6 is an enlarged detail sectional view, taken along the line 6 6 in Fig. 2.

`In accordance with this invention, a lap- -ping device for round objects may comprise aiiexible strip 'of abrasive material and a "support or holder therefor having a surface corresponding substantially to the shape of the object to be lapped and which is so ar- A further object of the invention is to proranged that it is capable of gripping the work piece while it is being rotated with the flexible abrasive material in lapping or abrading contact therewith. The support or l holder for the fiexible abrasive strip and thework piece preferably comprises a clamping device having two jaw members, each of which has a concave or hollow shoe capable of holding the iexible strip in abrading contact with the work. These jaws are movable toward and from one another to permit replacement of the work and they may be locked or secured in a definite operative relation to the piece of work when it is desired to lap or abrade the latter. In a machine of the type commonly employed for lapping crankshafts, as shown and fully described in the prior patent to Player No. 1,711,061 of April 30, 1929 to which reference may be had for a detailed description thereof, the work piece is supported at its ends and rotated by a suitable driving headstock and the lapping device oscillates on a jointed swinging carrier as the work revolves. yIn order that a supply of abrasive material may be maintained in suitable relation to the work piece, this material may be supported on a reel or mount which is preferably mounted on the lapping mechanism. One of the primary features of ythis invention is to move this strip of flexible abradingv material automatically to present a fresh sur- .face to the work piece, and preferably in timed relation with the movement of the support or clampingholder as the latter is moved 'tol and fromy an operative'position; andl for this purposeA a suitable feeding mechanism is'provided which will operate to feed( a measured invariable amount of the abrading material from the reeled supply for a given lapping operation. In ylapping' cylindrical objects of this type, it is necessary to open the jaws which hold the abrasive materia-lin contact with the work before a new piece'can be inserted, and a further feature of this invention involves the use of this operation for the purpose of feeding a fresh supply of abrading material through the lapping zone. One suitable way of accomplishing this is to provide a gripping device which engages the abrading paper and this gripping device-is moved automatically by movementof the clamping jaws and preferably when they are being opened.

The clamping jaws may be supported on'a jointed arm which is pivoted toa fixed portion of the machine.V These joints are necessarily freely movable so that when the jaws are unclamped from the work piece, the jointed members will permit the jaws to fall away. from an operative position. A further feature of this invention relates to the provision of `a device which will hold the clamping jaws near `the work when they are opened for replacement' of the work. This may be accomplished by means of a locking device which may be manually operated to lock or to release the swinging arms.

Referring more particularly to the drawing, one embodiment of this invention may comprise a flexible strip oscillatively supported on a base or stationary frame for lapping the pins of a rotating crankshaft. As shown, the work piece 10 may be held in operative contact with a flexible strip of abrading material 12, which is preferably anabrasive coated paper or cloth, and this strip is supported by a holder or support comprising, in the form illustrated, two concave jaw members 13 and 14 which are supported on arms 15 and 16 respectively. These arms 15 and 16 are pivotally supported on the T-head 18 of the jointed swinging arm comprising the arm member 19 which is pivotally jointed to the link 20, and the later is in turn pivotally mounted on a fixed part of the base or frame 22 of the machine which carries the crankshaft 10. In order that the flexible strip of abrasive material may be supported for movement through the lapping zone, a feeding rcel 25 is suitably mounted on the arm` 15 and a receiving reel 27 is mounted on the other arm 16. The flexible abrasive paper or cloth employed for the lapping or abrading operation is wound on the two reelsl and is loosely positioned in the lapping zone in such a manner that it may loop around the piece of work when the latter is inserted between the clamping jaws. When the jaws are clamped together, they will hold the abrasive material in contact with the work and as the work rotates between the jaws the surface thereof will be duly abraded.

The jaws 13 and 14 will, of course, be suitably shaped to conform approximately to the shape of the work, having due regard for the thickness of the abrasive material therebetween: and in order that the flexible strip of abrading material may be held firmly in position and prevented from movement during the lapping operation it is preferred to have the surfaces of the jaws frictionally engage this flexiblel strip, as may be accomplished by providing the jaws with a roughened surface. To this end, it is desirable to 'insert pieces of abrasive material'l 30 in grooves in the faces of the jaws. These pieces of abrasive 30 may be made of suitable material within the knowledge of those skilled in the art, and they are preferably sticks of ceramic bonded abrasive grains as are commonly employed in grinding wheels. If desired, the contacting portion of the sticks which grips the abrasive strip may be shaped to provide concave jaw faces having partial cylindrical surfaces conforming substantially to the outer surface of the flexible strip 12 when it engages the work.

mounted that they may be removed from the arms 15 and 16. The upper jaw 13 is sus` pended on the lower end of the post 32 which isvfreely mounted in the split clamping sleevel Therlower clamping jaw 14 is likewise mounted for a swivelling movement, it being sup; ported on the upper end off a post 38 which is pivoted within a socket in the arm 16.

In order that the operator may open or close the clamping jaws at will to release or engage a piece of work, the arms 15 and 16 are pivotally mounted by means of the pins 40 and 41 on the T-head 18, the pivot points 40 and 41 being located centrally of these arms. The links 43 and 44, which are pivotally connected by a pin 45, are pivotally mounted on the ends of the arms 15 and 16 respectively bymeans of the pivots 46 and 47 and serve for moving the arms together. The pin projects laterally from the links and slides in a slot 48 in the arm 19, the pin being held in position by suitable means, such as ahead thereon (not shown).

The operator may manually move the clamping jaws by means of a hand lever 50 pivotally mounted by means of a pin 52 on a -yoke 53 fixed on the clampingarm 15. The

lever 50 which llies between the members 55 `and 56, which.` compose the hand lever 50. are pivotally connected by means of a pin 57 ,to form a joint so as to compensate for the lengthening and shortening of thev hand lever during the opening and closing operation. That end ofthe lever member 55 which is connected to the link 56 will swing between the arms of the yoke 53 when the hand lever 50 is raised and so pull the link i 56 towards the yoke. The link 56 ispivotally connected to the link 43l by means of the pin 60, so that movementv of the lyinkto the left (Fig. 1)Lwi,ll move pin 45 towards the right and lower the clamping jaw y13. The jointed members 55 and 56 havecooperating fiat faces 61 which engage when the members are in alignment and serve to prevent further opening movement when the clamping jaws 15 and 16 have bee suiiiciently separated. Any upward motion of the hand lever.

50 to close the clamping jaws will break the joint and -permit the linkr56 to move about the pivot points 57 and 60 to reduce the effective. length of that portion of thehand pivot Pin 52 and theoperating link 43.. l l

In order that the connecting Alink.20 carrying the lapping device may be supported when the clamping jawsare disengaged from the work piece, a locating pin is suitably xed to a "rotatableshaft 71 and is adapted` to be swung from a depending and Ain the path of the link 20 and thereby prevent the arm from (y swinging to its full extent toward the right, asviewed in Fig. 1. The

shaft 71 is freely mounted in suitable bearings on the frame 22 of the machine for rotation by a crank 74 suitably attached thereto. The crank 74 is oscillated by a link 7 5, which has its respective end portions pivotallyconnected by pins 76 nd 77 to the crank 74 and the arm 78 of the'hand'lever 79. The hand lever 79 is pivotally mounted on the frame 22 by a pin 80, so that an upward movement of the hand lever 79 will rotate the shaft 71 and swing the pin 70 to the position shown in the dotted outline in Fig. 1 thereby remov- -ng the ypin 70 from engagement with the link 20.

A locking device is employed to hold the arm 19 of the lapping device in a horizontal position after it has been withdrawn lfrom .the work piece` and the link 20 has been located bythe pin 70. As shown in Fig. 2,

a lever 85 is pivotally mounted on the arm member 19 by means vof a pin 86 centrally disposed thereof. One end of this lever 85 is provided with teeth 87 which engagea correspondingly toothed member 88 att ched to the link 20 and thereby lock the arm 9 in the desired position. lDuring the normal lapping operation the clamping jaws 13 and 14 are held in the closed position, as shown in Fig. 2, and the pivoted arm 85 is held out n .of engagement with the toothed member 88 by means of the spring 90 .and movement of( 100 the lever 85 is limited by a stop 91 set in\ the arm 19.

In order to move the locking lever 85 into engagement with the toothed member 88, the link 43 is provided with an extension 95 having a contact surface 96 which engages a pin 97 slidably positioned in a slot l98 within the lever 85 held in contact with the surface by means of a spring 99. It can readily be seen that, with the opening ofthe clamping jaws `15 and 16, an upward movement of the hand lever 50 will bring the surface 96 into contactwith the pin 97 thereby causing the lever v relation with and preferably by movement of the jaws when they are moved to releaseethe work. This device as illustrated includes a feeding vtool 101 located between a pair of guideways 102 (Figs. 3 and4) /which are suitably "fastened to the side of the lowerV arm16, and pivotally mounted on a pin 104, the two ends of which project -through and are slidable in the slots 105.in the two guide- .ways 102. This feeding tool 101 isL-shaped (Fig. 4) and carries a serrated portion 106 at one end which contacts with the abrasive strip 12. This strip passes along. the lower edge of' the arm 16 and rests against a substantially at portion 107 of the lower surface ofthe arm 16 between the guideways 102. The feeding tool is arranged to reciprocate in one direction in frictional feeding contact with the strip 12 and to travel freely over the strip when it travels in the opposite direction, and thereby feed the strip only in 011e direction. The tool is moved by means of `the link 108 connected thereto by a pin 109. A spring 111 between the link 108 and the tool 101 holds the tool in frictional engagement with the abrasive strip 12. The crank 110 connected to drive the arm 108 is pivotally mounted on the arm 16 by means of a stud 112 and adapted to be moved by of reciprocation of the feeding tool 101'and CTI consequently regulate the amount of the strip which is fed at one time. The link 113 is pivotally connected to the crank 110 (Fig. 5) by means of a pin 115.

In order that the used abrading material may be removed from the lapping zone, the receiving reel 27 is rotatably mounted on the lower portion of the arm 16, 'and it is arranged to be rotated by movement of the crank 110. The used portion of the strip 12 should be wound onto the reel at the same rate as it is fed through the lapping zone. For

this purpose the ratchet wheel 116 attached to one end of the reel -27 is adapted-to be rotated by means of a pawl 117 which is pivotally mounted on the pin 115 connecting the crank 110 with the link 113. It can be seen that any movement of the crank 110 to produce a feeding of the paper 12 will also cause a corresponding movement of the pawl 117, thereby rotating the reel 27 to reel up the used material which would otherwise hang down over the feeding tool 101 atthe end of the feeding stroke.

The reel 27 isrotated at a uniform angular rate irrespective of the diameter of the reeled strip 12, hence provision must be made to permit slippage between the reel and the driving mechanism, when the paper tends to be drawn too tightly. As shown in Fig. 6, the ratchet wheel 116 has an elongated hub 118 which is mounted on'a stud 119 attached to the lower arm 16. A disk 120 surrounding and supported by the hub 118 is suitably pinned to the ratchet wheel 116 to turn therewith and yet form a side support against which the used portion of the strip 12 may build up during the winding operation. A sleeve 122,'serv1ng as a spool on which the used abrasive strip is wound after it has been drawn along by the feeding tool 101, is rotatably supported on the hub 118 and there secured against endwise movement by a ring 123 placed within a cavity in the sleeve 122 and locked to the stud 119 by means of a washer 124 secured to the stud 119 by a screw 125. In order to provide suitable driving connections between the ratchet wheel 116 and the sleeve 122, a friction washer of fibrous material 126 is placed between the guard 120 and the adjacent end of the sleeve 122. This end portion of the sleeve 122 is held in engagement with the washer 126 by means of helical springs 127 which are located within recesses y in the sleeve 122 and furnish sufficient pressure to hold the sleeve in frictional driving Contact with theratchet wheel 116 and`to wind the strip onto the spool. The friction of material and that the ratchet 116 is turned through the same angular distance for each movement of the feeding tool 101. The ratchet wheel 116 is prevented from turning when the arm 117 is moved backwards to a new position by a pawl 130 (Fig. 2) pivotally mounted on the arm 16 and held in engagement with the ratchet wheel by means of a spring 131 supported on apin 132 and attached to the sides of the arm 16. In order to prevent the abrasive material from being carried back after it has been dragged along by means of the feeding tool 101, a triangular stop 135 (Fig. 2) is pivotally mounted in a cavity 136 within the arm 16 and hung downwardly so that the lower corner engages the upper surface of the abrasive material 12, thereby holding the paper against the top of the piece 137, which connects the guides 102, during the return stroke of the feeding tool 101 to its initial feeding position.

Theupperreel 25 maybe suitablyconstructed as a metal spool rotatably supported within the hollow shell formed ofthe cap 140 pivoted at 141 to the extension 142 on the arm 143 which is secured by a cap screw` 144 to the arm 15. The cap 140 and extension 142 are shaped to provide a cylindrical chamber within which the reel is loosely positioned. An opening 145 is formed between the lower depending ends 146. and 147A of the cap 140 Aand the extension 142. These ends have adjacent flat faces engaging the opposite sides ofthe flexible strip and are held in frictional contact therewith by the spring 148 which forces the cap 140 towards the opposite member. This arrangement is such that the flexible strip will not unwind ,readily from the reel and the rotary motion ofthe work will not draw more of the strip into the lapping zone.

When the operator wishes to remove the 'lapping device from the work piece at the completion of the lapping operation, the hand lever 50, which is in a vertical position at this time, is pulled downwardly toward the operator causing the link 55 to move about the pivot 52 to impart movement to the l0 link 43 attached to the upper lapping arm 15. The links43 and 44, which are in vertical positions during the grinding operation, serve as they move to slide the pin 45 along the slot 48, thereby rocking the arms and 15 16 about their respective pivot points 40 and 41 and opening the clamping jaws of the lapping device. This movement of the link 44 imparts movement to the arm 113 and oscillatesthe crank 110, and so actuates both the feeding tool 101 and the reel 27. As shown in Fig. 4, the pin 109 of the feeding tool 101 is positioned belowy but to one side of the' pivot 108 toward the reel 27 will produce a turning movement of the feeding tool 101 about the pivot 104, thereby digging the teeth 106 of the feeding tool 101 into the outer surface of the flexible abrasive strip 12, as the tooll 101 is reciprocated, and so dragging the strip toward the reel 27. Simultaneously with the movement of the feeding tool 101, the crank 110 reciprocably moves the paw] 117 attached thereto so that by means of the cooperating toothed members on the ratchet wheel 116 and the pawl 117, the reel is rotated to wind up the used portion of the abrasive strip 12 at the same rate that it is drawn along by the feeding tool 101.

The linkage employed between the hand lever and the feeding mechanism is exceedingly positive and such that a slight movement of the hand lever 50 will open the clamping jaws 13 and 14 simultaneously with the movement of the feeding tool 101, to thereby replace a small portion ofthe flexible a rasive strip between the jaw members. `Further downward movement of the hand lever 50 to completely open the jaw members 13 and 14 will further feed the abrasive `50 strip through the lapping zone. This move- ,ment will continue until the extension 95 of the link 43 engages the spring pressed pin 97 attached to one end of the pivoted arm-85, so that additional movementv of the hand lever downwardly will move the extension 95 downwardly thereby vccljliressing the nin 97, which after seating, 85 about its pivot 86 to brng`the teeth 87 into engagement with the toothed member* 88 attached to the link 20, thereby locking the arm 19 in a horizontal positionso that the P clamping jaws will be in approximatelya correct position for engaging a new work piece and so make it unnecessary for the vop- 5 erator to reposition the clamping jaws.

pin 104 so that movement of the arm move the lever After the lapping device has been removed from the work piece 10 and the arm 19 locked in a horizontal position, the operator moves the hand lever` 79 forwardly to move it about the pivot 80 to thereby actuate the link 75 and rotate the shaft 71 in a clockwise direction, thus swinging the depending pin 70 up t'o a horizontal position' in the path ouf the link 20 and so forming an effective rest for the link 20 `as it swings rearwardly after the plece.

When the work piece has been placed inl position, the lapping device, which has now had the abrasive material in its lapping zone renewed, is grasped by the operator and drawn forwardly from engagement with the pin 70 and the jaw members 13 and 14 positioned over the work piece 10. The handl lever 50 is thrown upwardly thereby mov` ing the link members 43 and 44 to a vertical position so that the arms 15 and 16 move towards each other and force the jaw m'embers 13 and 14 about the work piece 10. The hand lever 79 is thrown approximately to a vertical position to revolve the pin 70 to the vertical position as shown in dotted outline in Fig. 1 at which position it remains during the lapping operation. As previousl explained, the link 20 is attached to the rame 22 by suitable pivots and is loosely jointed.

to be lapped, feeding and receiving mounts,"

one being located on each ofthe jaws to sup- 'f5 lapping head is disengaged from the work uns port and retain the ends of a flexible strip of abrasive material and hold it in operative relation with the work, means for opening and closing the jaws, and means operated in timed'relation vwith the movement of the jaws to move a measured invariable amount of the abrasive strip for each operation of the jaws and present a fresh portion to the work and to feed the used portion of the strip to the receiving mount.

2. A lapping device comprising a iexible strip of abrasive material, two jaws having surfaces conforming substantially `to the curve of the work to be lapped, a reel-suported on each of said jaws arranged to hold said 4iexible abrasive strip in operative relation'with the work, means for opening and closing said` 'aws, andmeans moved by said movement of the jaws to feed an invariable l measured amount of said flexible strip to i to feed a measured invariable amount of the strip f or each jaw movement to present a fresh surface to the work, a reel, and means to wind the strip on the reel progressively as it is fed.

4. A lapping device comprising ya flexible strip of abrasive material, a support therefor movable to and from an operative position in which it holds the strip in operative contact with the work, a feeding reel, a receiving reel, means for frictionally retarding the movement of the strip from the feeding reel, and means operated by movement of the support for automatically winding a measured amount of the strip on the receiving reel.

5. A lapping device comprising a flexible strip of abrasive material, a feeding reel and a receiving reel to hold the ends of the strip, a support movable to and from an operative position in which it holds the strip in abrading contact with the work, means operated in timed relation with the movement of said support to feed a measured amount of the strip from one reel to the other, and means cooperating with the reels to prevent feeding of the strip during the lapping operation.

6. A lapping device for an eccentrically revoluble piece of work comprising a support for a flexible abrasive strip, a frame, a jointed carrier pivotally mounted on said frame'and carrying said support which is so arranged that the strip may contact with the work as it revolves, andyreleasable means for holding the carrier and the support in a definite position relative to the work.

7. A lapping device comprising a frame, a support for a lapping element, an arm carrying the'support, a link pivotally connecting said arm with the frame' and movable so that the lapping element may contact with a piece of work while it revolves eccentrically, a releasable locking member to hold the arm in a fixed position relative 'to the link, and means on the frame-to hold said link in a definite position, whereby the lapping element may be located relative tc a piece of work. i

8. A lapping device comprising'a flexible strip of abrasive material, a holder vtherefor movable to and from an operative position in which it holds the strip in operative contact with the work, a receiving Vrech-:means:operated in timed relation with the movement of said holder to feed a portion of the worn strip to the reel and thereby feed a predetermined length of fresh abrasive material to the lapping zone, and means -to retard the movement of the strip from the reel.

l9. A lapping device comprising a flexible strip of abrasive material, a holder therefor movable to nd from an operative position in which it holds the abrasive strip in operative contact With the Work, a feeding' reel, a receiving reel, means for frictionally retarding the movement of the strip from the feeding reel, and means positively actuated by the movement of said holder to wind a predetermiilied length of the strip on the receiving ree 10. A lapping device comprising a flexible strip of abrasive material, a feeding reel and a receiving reel to hold the ends of the strip, a holder movable to and from an operating position in which it holds the strip in abradfeeding member operated in timed relation with the movement of said holder to feed a measured amount of abrasive material from the feeding reel` means positively driven by said feeding tool to Win d the abrasive strip on the receiving reel, and means cooperating with the receiving reel to prevent winding the strip at a rate different from that at which it is fed by said tool.

11. A lapping device comprising a flexible strip of abrasive material, a support for said strip movable to and from an operative position relative to the work, mechanism operated by movement of said support for feeding a measured amount of said strip, and means associated with said mechanism and said support to regulate the amount of the strip which is fed by one movement of said support.

12. A lapping device for a cylindrical object comprising a flexible strip of abrasive material, a support for said strip movable to ing contact with the work, a reciprocable 'p85 and from an operative. position relative to Y one arm, a reel mounted on a second arm, a

strip of abrasive material woundl on one reel and extending across the ends of the arms and onto the second reel, end faces on said arms the shape of which conforms to the bearings, said abrasive material extending between said faces and bearings when the parts are in operative position, and means including'a pawl and toothed member for automatically feeding an invariable measuredy `amount of said abrasive material from one 

